1. Field of the Invention
This invention generally relates to wireless communications and, more particularly, to a system and method for creating a picocell as an alternative to a multiple access wireless network service.
2. Description of the Related Art
Air travel has become an integral part of our lives. Today, airplanes seem to be the last remaining island where mobile communications and Internet access are not always available. Market surveys of in-flight network providers show the desirability of high-data rate communication services for airliners, with an obvious trend towards in-flight entertainment (IFE), Internet applications, and personal communications.
Further, people are becoming more accustomed to their own personalized equipment, such as mobile phones, laptops, or PDAs, all accommodated with their own personal environment. Future airliners will provide a variety of entertainment and communications equipment to the passenger to make the journey more pleasant through in-flight entertainment, more productive through business communication facilities, and more secure through tele-medicine and surveillance facilities on board.
In addition, a plane full of “captive” travelers may be quite alluring to advertisers, especially since the Web pages that passengers see can be tailored to their destination, be it a trade show, tourist site, or even just a city that wishes to publicize its amenities.
Thus, thinking of future mobile communication from a user acceptance point of view, there is a clear demand for a wireless access solution for multimedia and personal communication services through the user's own equipment.
The use of conventional cellular and PCS phones are prohibited in commercial aircraft, while the aircraft is in the air. Allowing an aircraft-borne phone to communicate with terrestrial cells is not desirable, as the phones must transmit at a relatively high power with a communicating terrestrial cell, and may interfere with other, adjoining cells on the ground.
As noted in U.S. Pat. No. 6,144,653, Persson et al., a typical cellular telephone system divides a geographical area into several smaller, contiguous radio coverage areas called “cells.” The cells are served by a series of fixed radio stations called base stations. The base stations are connected to, and controlled by a mobile services switching center (MSC). The MSC, in turn, is connected to the landline public switched telephone network (PSTN). The telephone users (mobile subscribers) in the cellular radio system are provided with portable (hand-held), transportable (hand-carried) or mobile (car-mounted) telephone units (mobile stations) that communicate voice and/or data with the MSC through a nearby base station. The MSC switches calls between and among landline and mobile subscribers, controls signaling to the mobile stations, compiles billing statistics, and provides for the operation, maintenance, and testing of the system.
The base stations are located at the center of the cells and are equipped with omni-directional antennas transmitting equally in all directions. In some circumstances, a base station may be located near the periphery of a cell, or it may illuminate the cells with directional radio signals directionally. Each of the base stations is connected by voice and data links to a mobile services switching center (MSC) which is, in turn, is connected to a central office in the public switching telephone network (PSTN), or a similar facility, e.g., an integrated system digital network (ISDN). A plurality of mobile stations may be found within the cells. Mobile subscribers may travel from one location in a cell to another or from one cell to an adjacent or neighboring cell.
Each of the cells is allocated a set of the channels assigned to the entire cellular system by a concerned government authority, e.g., the Federal Communications Commission (FCC) in the United States. The channels are used to support voice, data, and paging/access or control channels between each of the base stations and the mobile stations in its coverage area. The link between base station and mobile unit is bidirectional. Therefore, separate channels are assigned to a mobile station and base station for transmission. When in the idle state (turned on but not in use), each of the mobile stations tunes to and then continuously monitors the strongest control channel (generally, the control channel of the cell in which the mobile station is located at that moment) and may receive or initiate a telephone call through one of the base stations. When moving between cells while in the idle state, the mobile station will tune to the control channel of the strongest cell. The initial tuning to, and the change of control channel is accomplished automatically by scanning all the control channels in operation in the cellular system to find the strongest control channel. When a control channel with good reception quality is found, the mobile station remains tuned to this channel until the quality deteriorates again.
While in the idle (standby) state, each of the mobile stations continuously determines whether a page message addressed to it has been received over the control channel. The called mobile station with the matching identification automatically transmits a page response over the control channel to the base station, which forwards the page response to the MSC. Upon receiving the page response, the MSC selects an available voice channel in the cell from which the page response was received, turns the selected voice channel transceiver on, and requests the base station in that cell to order the mobile station via the control channel to tune to the selected voice channel. A through-connection is established once the mobile station has tuned to the selected voice channel.
Similar control procedures exist for code division multiple access (CDMA), time division multiple access (TDMA) frequency division multiple access (FDMA) systems such as Global System for Mobile communications (GSM), or UMTS networks, to name a few examples.
The concept of a variable cell sizes has been applied to multiple access telephone networks, classifying cells into a megacell, macrocell, microcell, minicell, or picocell according to the size. A picocell is typically employed to provide an in-building communication service, and provide a communication service to a limited area such as campus, stadium, airport and shopping mall. Further, the picocell is used to compensate for deterioration of the service quality of the macrocell, due to topographical obstacles such as a tunnel, to increase the communication quality in an area with a low communication quality.
The advent of spread spectrum systems such as CDMA2000, Universal Mobile Telecommunications System (UMTS), and low power picocell access, offers potential avenues to further the use of conventional wireless telephones in aircraft. Further, potential solutions may stem from new aircraft avionics technologies inline with aircraft development.
It would be advantageous if a picocell could be formed in special circumstances, such as in an aircraft cabin, without interfering with conventional terrestrial multiple access telephone network communications.
It would be advantageous if the above-mentioned picocell could provide mobile stations, in controlled spaces or zones, with the same services as provided by the conventional multiple access telephone networks.